The invention relates generally to power tools, and more specifically to a supporting and stabilizing shoe for a masonry circular saw.
Hand saws have been used for centuries to cut wood and other materials. Hand saws require a user to manually move a blade in a reciprocating motion against a workpiece along a line, and this action divides a larger workpiece into smaller pieces. Because hand saws are gripped by the hand of a worker, they are designed to be controllable by the average person. In recent years power saws have been developed with a blade attached to a motor to drive the blade in rotary or reciprocating motion. Power saws allow a user rapidly to cut a workpiece, such as wood, metal, masonry or any other material, but are normally very heavy and/or large, thereby making them somewhat difficult to control.
Common power saws include chainsaws, which are typically used to saw wood to rough dimensions. Chainsaws include an internal combustion or electric motor mounted to a rigid frame and enclosed in a housing. An elongated, flat bar extends from the frame with a looped chain, driven by the motor, slidably mounted in a groove around the bar. There are also circular saws for masonry use, for example to cut stone, concrete or other masonry material. Such masonry circular saws, which include the STIHL brand model TS420 as an example, have an internal combustion engine mounted to a frame, housing and drive mechanism, much like a chainsaw. However, the drive mechanism mounts to a circular masonry blade, which can be diamond tipped, rather than a bar and chain.
It is necessary with any saw to drive the blade at a desired and consistent angle through the workpiece. Additionally, the blade is preferably maintained at a consistent depth in the workpiece during cutting. With a masonry power saw, controlling the angle and depth of the blade can be difficult because such saws are, like chainsaws, heavy and held by hand. Workers manually maintain the angle and depth of the blade in the workpiece, but this results in fatigue and injury.
The cutting blades of masonry power saws are spaced from the engine so that one holds the housing of the engine, and the blade is spaced from the housing away from the user. This configuration results in control over the masonry power saw that is similar to that of a typical chainsaw. For rough cutting of masonry, the conventional masonry power saw is sufficient. However, for precise cutting, the masonry power saw is difficult to control.
Wood-cutting circular saws commonly have blades mounted directly to the driveshaft of the motor, adjacent to the housing of the motor and not spaced from the motor. This enables a pivoting shoe to be attached to one housing end, extend beneath the housing around the blade, and attach at the distal housing end. This configuration provides a stable and strong support for the weight of the wood-cutting circular saw. Wood-cutting circular saws are often used for precise cutting of wooden workpieces.
It is thus known to attach a shoe to a saw that has a circular blade attached directly to the driveshaft of the motor that drives the blade, as shown in U.S. Pat. Nos. 6,112,736, 5,540,210 and 4,022,182 for wood-cutting circular saws. However, to Applicant's knowledge no such shoe is known for masonry power saws, which have substantially different configurations than the typical wood-cutting circular saw.